Technical Field
The present invention relates to an optical fiber.
Related Art
In the field of interconnecting, optical fibers are required to have such fatigue resistance that even when the optical cable is bent to, for example, a radius as small as 1.5-2 mm, the optical fiber in this optical cable is less apt to fatigue.
For obtaining satisfactory fatigue resistance, it is effective to reduce the glass-fiber diameter of the optical fiber. Although optical fibers usually have a glass-fiber diameter of 125 μm, use of an optical fiber having a glass-fiber diameter smaller than 125 μm can improve the fatigue resistance (see, for example, Japanese Patent No. 3902201, Japanese Patent No. 3518089, and U.S. Pat. No. 8,189,978).
Japanese Patent No. 4341872 describes a liquid radiation-curable resin composition for the inner primary coating of optical fibers, the resin composition containing an oligomer having a reactive group at each of both ends.